1. Field of the Invention
The present invention relates to a source reagent composition and method for the formation of Zr/Hf silicate thin film gate dielectric structures for microelectronic devices.
2. Description of the Related Art
The formation of stable gate dielectric thin films is an increasingly important focus of microelectronic device research and development efforts.
Zirconium silicate (ZrSiO4) and hafnium silicate (HfSiO4) are potentially useful materials for such gate dielectric thin films on silicon substrates. The source reagents and methodology employed to form such gate dielectric thin films are extremely critical for the provision of a gate structure having satisfactory characteristics in the product device. Specifically, the source reagents and methodology must permit the gate dielectric thin film to form on a clean silicon surface, without the occurrence of side reactions producing predominantly silicon dioxide (SiO2), locally doped SiO2 and/or other surface impurities that lower the dielectric constant and compromise the performance of the product microelectronic device.
The present invention relates in one aspect to a precursor composition for forming a metal silicate thin-film dielectric on a substrate, such precursor composition including a source reagent selected from the group consisting of:
(a) single source precursors for forming zirconium silicate thin films, wherein the precursor is a compound or coordinated complex containing Zr, O and Si as constituents thereof;
(b) single source precursors for forming hafnium silicate thin films, wherein the precursor is a compound or coordinated complex containing Hf, O and Si as constituents thereof;
(c) a precursor mixture comprising (1) a first precursor metal compound or complex including a silicon alcoxide (siloxide) ligand coordinated to a metal M, wherein M=Zr or Hf and (2) a second precursor metal compound or complex including an aliphatic alcoxide ligand coordinated to a metal M, wherein M=Zr or Hf, wherein the relative proportions of the first and second precursors relative to one another are employed to controllably establish the desired M/Si ratio in the deposited silicate thin film;
(d) a precursor mixture comprising (1) a first precursor metal compound or complex including a metal M, wherein M=Zr or Hf and (2) a second precursor silicon compound or complex not containing such metal M, wherein the relative proportions of the first and second precursors relative to one another are employed to controllably establish the desired Mx/Si1xe2x88x92x ratio in the deposited silicate thin film, wherein x is from about 0.01 to 0.99;
(e) a precursor mixture comprising (1) a first precursor metal compound or complex including a metal M, wherein M=Zr or Hf and (2) a second precursor silicon compound or complex additionally containing such metal M, wherein the relative proportions of the first and second precursors relative to one another are employed to controllably establish the desired Mx/Si1xe2x88x92x ratio in the deposited silicate thin film, wherein x is from about 0.01 to 0.99;
(f) a precursor metal compound or complex including a metal M, wherein M=Zr or Hf, at least one alcoxide ligand and at least one xcex2-diketonate ligand, such precursor metal compound or complex optionally further containing silicon;
(g) the precursor metal compound or complex (d) wherein the second precursor silicon compound or complex not containing such metal M is a gas at STP, e.g. silane, and the relative proportions of the first and second precursors relative to one another are employed to controllably establish the desired Mx/Si1xe2x88x92x ratio in the deposited silicate thin film, wherein x is from about 0.01 to 0.99;
(h) a precursor metal compound or complex including a metal M, wherein M=Zr or Hf, at least one alcoxide ligand and at least one xcex2-diketonate ligand, such precursor metal compound or complex optionally further containing silicon;
(i) the precursor metal compound or complex (e) not containing silicon, in combination with a second silicon-containing precursor compound or complex;
(j) the precursor metal compound or complex (e) further containing silicon, in combination with a second non-silicon-containing precursor metal compound or complex including a metal M, wherein M=Zr or Hf; and
(k) compatible mixtures of any two or more of the foregoing species (a)-(i).
The precursor composition may further comprise a solvent medium, e.g., a solvent selected from the group consisting of ethers, glymes, tetraglymes, amines, polyamines, alcohols, glycols, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, cyclic ethers (e.g., tetrahydrofuran, etc.), and compatible combinations of two or more of the foregoing.
Another aspect of the invention relates to a method of forming a metal silicate gate dielectric film on a substrate, comprising vaporizing a precursor composition to form a precursor vapor, and contacting the precursor vapor with a substrate at elevated temperature to deposit the metal silicate gate dielectric film on the substrate, wherein the precursor composition includes a source reagent selected from the group consisting of:
(a) single source precursors for forming zirconium silicate thin films, wherein the precursor is a compound or coordinated complex containing Zr, O and Si as constituents thereof;
(b) single source precursors for forming hafnium silicate thin films, wherein the precursor is a compound or coordinated complex containing Hf, O and Si as constituents thereof;
(c) a precursor mixture comprising (1) a first precursor metal compound or complex including a silicon alcoxide (siloxide) ligand coordinated to a metal M, wherein M=Zr or Hf and (2) a second precursor metal compound or complex including an aliphatic alcoxide ligand coordinated to a metal M, wherein M=Zr or Hf; wherein the relative proportions of the first and second precursors relative to one another are employed to controllably establish the desired M/Si ratio in the deposited silicate thin film;
(d) a precursor mixture comprising (1) a first precursor metal compound or complex including a metal M, wherein M=Zr or Hf and (2) a second precursor silicon compound or complex not containing such metal M, wherein the relative proportions of the first and second precursors relative to one another are employed to controllably establish the desired M/Si ratio in the deposited silicate thin film;
(e) a precursor mixture comprising (1) a first precursor metal compound or complex including a metal M, wherein M=Zr or Hf and (2) a second precursor silicon compound or complex additionally containing such metal M, wherein the relative proportions of the first and second precursors relative to one another are employed to controllably establish the desired M/Si ratio in the deposited silicate thin film;
(f) a precursor metal compound or complex including a metal M, wherein M=Zr or Hf, at least one alcoxide ligand and at least one xcex2-diketonate ligand, such precursor metal compound or complex optionally further containing silicon;
(g) the precursor metal compound or complex (d) wherein the second precursor silicon compound or complex not containing such metal M is a gas at STP, e.g. silane, and the relative proportions of the first and second precursors relative to one another are employed to controllably establish the desired Mx/Si1xe2x88x92x ratio in the deposited silicate thin film, wherein x is from about 0.01 to 0.99;
(h) the precursor metal compound or complex (e) not containing silicon, in combination with a second silicon-containing precursor compound or complex;
(i) the precursor metal compound or complex (e) further containing silicon, in combination with a second non-silicon-containing precursor metal compound or complex including a metal M, wherein M=Zr or Hf; and
(j) compatible mixtures of any two or more of the foregoing species (a)-(i).
As used herein, the term xe2x80x9cthin filmxe2x80x9d refers to a material layer having a thickness of less than about 100 microns.
Other aspects, features and embodiments of the invention will be more fully apparent from the ensuing disclosure and appended claims.